Our zoom function zooms to the cursor, so it can be disorienting at first (you'll get used to it in no time -- I hope). If you zoom around and get lost using the mouse -- try clicking the center mouse button once. It'll immediately zoom extents.

You can also use the + and - keys on the numeric keypad. It still zooms while centering on the cursor, but with a zoom factor of 1.1 or 1.2 it might be easier to get a feel for it.

Also, you might try Tools - Customize. Then click on Aliases and select the category Zoom under the View menu. You will see the different zooms and you could set Zoom Window to have the keyboard alias of Z.